40 fire engines and around 225 firefighters tackled a fire at a block of flats on Freshwater Road in Dagenham.
The whole of the building was affected by the fire, including scaffolding surrounding the property and the roof.
London Fire Commissioner Andy Roe said: “We were called to the incident at 0244 this morning.
“The first crew arrived within five minutes and the second crew arrived within six minutes. An aerial appliance also arrived in under six minutes. To allow us to focus our resources on the incident, we declared a major incident, which has now been stood down. I am immensely grateful to the crews and officers who have operated in the most dangerous conditions to both rescue people and bring the incident under control despite being faced with a significant building failure.
"The building has a number of fire safety issues known to London Fire Brigade. A full simultaneous evacuation of the building was immediately carried out and a significant search and rescue operation took place.
“I am pleased to confirm that everyone has been accounted for. More than 80 people were evacuated with firefighters leading residents out to safety and carrying out 20 rescues. This included using fire escape hoods, which can provide 15 minutes of clean, filtered air in smoke-filled environments, helping individuals stay safe until they can be rescued or reach safety. Four people were treated on scene by London Ambulance Service crews, with two taken to hospital for smoke inhalation.
“The Brigade’s Control Officers took 16 calls to the fire, including successfully giving vital fire survival guidance to a number of people using our Fire Survival Guidance App, which allows information to be exchanged between Control and the incident ground in a timely, accurate and consistent manner. They are also to be commended for their calm professionalism as the building began to fail.
“We also used new equipment such as drones and our 64-metre and 32-metre turntable ladders to provide incident commanders with a vantage point for assessing the scene. They were also used as water towers to deliver water on to the fire from above.
“The Brigade stood up full strategic arrangements to deal with the incident and a rest centre has been set up at Becontree Heath Leisure Centre. London Fire Brigade officers and members of our dedicated community support team are stationed at the rest centre to support residents alongside partners. Crews will also remain on scene into tomorrow carrying out further operations.
“We have commenced a full and detailed investigation into the cause of this fire, and we are working closely with police colleagues. However, due to the extensive damage to the building with parts of it now being declared unsafe, access may be limited. This will be a protracted investigation and our fire investigation and fire safety officers are likely to be on scene for several days. We know there will undoubtedly be concerns around potential fire safety issues, and this investigation will be a priority for our officers over the coming weeks.
“Our thoughts are with all those who have been affected and we will remain present in the local community throughout the coming days to provide support where needed.
"I would like to take this opportunity to thank our crews, Control Officers, fire safety officers and support staff who worked incredibly hard to resolve the incident and to ensure everyone was safe. I would also like to thank our partners for their support.”
The Brigade was called at 0244 and the fire was under control by 1113. Fire crews from Dagenham, Ilford, Romford, Barking and surrounding fire stations attended the scene. The major incident was stood down at 1103.